An increase in the level of 2-oxoglutarate promotes heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120

Microbiology ◽  
2003 ◽  
Vol 149 (11) ◽  
pp. 3257-3263 ◽  
Author(s):  
Jian-Hong Li ◽  
Sophie Laurent ◽  
Viren Konde ◽  
Sylvie Bédu ◽  
Cheng-Cai Zhang
Keyword(s):  
Inorganic Nitrogen ◽  
Cell Types ◽  
Filamentous Cyanobacterium ◽  
Nitrogen Status ◽  
Gene Encoding ◽  
Combined Nitrogen ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Heterocyst Development

In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, a starvation of combined nitrogen induces differentiation of heterocysts, cells specialized in nitrogen fixation. How do filaments perceive the limitation of the source of combined nitrogen, and what determines the proportion of heterocysts? In cyanobacteria, 2-oxoglutarate provides a carbon skeleton for the incorporation of inorganic nitrogen. Recently, it has been proposed that the concentration of 2-oxoglutarate reflects the nitrogen status in cyanobacteria. To investigate the effect of 2-oxoglutarate on heterocyst development, a heterologous gene encoding a 2-oxoglutarate permease under the control of a regulated promoter was expressed in Anabaena sp. PCC 7120. The increase of 2-oxoglutarate within cells can trigger heterocyst differentiation in a subpopulation of filaments even in the presence of nitrate. In the absence of a source of combined nitrogen, it can increase heterocyst frequency, advance the timing of commitment to heterocyst development and further increase the proportion of heterocysts in a patS mutant. Here, it is proposed that the intracellular concentration of 2-oxoglutarate is involved in the determination of the proportion of the two cell types according to the carbon/nitrogen status of the filament.

Identification of the oriC region and its influence on heterocyst development in the filamentous cyanobacterium Anabaena sp. strain PCC 7120

Microbiology ◽  
2011 ◽  
Vol 157 (7) ◽  
pp. 1910-1919 ◽  
Author(s):  
Yin Zhou ◽  
Wen-Li Chen ◽  
Li Wang ◽  
Cheng-Cai Zhang
Keyword(s):  
Regulatory Function ◽  
Filamentous Cyanobacterium ◽  
Chromosomal Dna ◽  
Unicellular Cyanobacterium ◽  
Prolonged Incubation ◽  
Combined Nitrogen ◽  
Oric Region ◽  
Cyanobacterium Anabaena ◽  
Pcc 7120 ◽  
Heterocyst Development

Anabaena sp. strain PCC 7120 (Anabaena PCC 7120) is a filamentous, nitrogen-fixing cyanobacterium. Upon deprivation of combined nitrogen, about 5–10 % of the cells become heterocysts, i.e. cells devoted to N2 fixation. Heterocysts are intercalated among vegetative cells and distributed in a semi-regular pattern, and adjacent heterocysts are rarely observed. Previously, we showed that the cell cycle could play a regulatory function during heterocyst development, although the mechanism involved remains unknown. As a further step to understand this phenomenon, we identified the oriC region for chromosomal DNA replication, located between dnaA and dnaN. The oriC region of Anabaena PCC 7120 was able to support the self-replication of a plasmid in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Surprisingly, integration of the oriC region into the chromosome of Anabaena PCC 7120 through homologous recombination led to much slower cell growth in the absence of a combined-nitrogen source and to multiple contiguous proheterocysts after prolonged incubation. Real-time RT-PCR showed that expression of two heterocyst-related genes, hetR and hetN, was altered in these strains: hetR expression remained high 48 h after induction, and hetN increased to high levels after induction for 12 h. These results suggest that the balance between oriC and DnaA could be important for heterocyst development.

scholarly journals Manipulation of Pattern of Cell Differentiation in a hetR Mutant of Anabaena sp. PCC 7120 by Overexpressing hetZ Alone or with hetP

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 60 ◽  
Author(s):  
He Zhang ◽  
Xudong Xu
Keyword(s):  
Cell Differentiation ◽  
Peptide Inhibitor ◽  
Filamentous Cyanobacterium ◽  
Heterocyst Differentiation ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

In the filamentous cyanobacterium, Anabaena sp. PCC 7120, single heterocysts differentiate at semi-regular intervals in response to nitrogen stepdown. HetR is a principal regulator of heterocyst differentiation, and hetP and hetZ are two genes that are regulated directly by HetR. In a hetR mutant generated from the IHB (Institute of Hydrobiology) substrain of PCC 7120, heterocyst formation can be restored by moderate expression of hetZ and hetP. The resulting heterocysts are located at terminal positions. We used a tandem promoter, PrbcLPpetE, to express hetZ and hetP strongly in the hetR mutant. Co-expression of hetZ and hetP enabled the hetR mutant to form multiple contiguous heterocysts at both terminal and intercalary positions. Expression of hetZ, alone resulted in terminally located heterocysts, whereas expression of hetP, alone produced enlarged cells in strings. In the absence of HetR, formation of heterocysts was insensitive to the peptide inhibitor, RGSGR.

scholarly journals Anabaena sp. Strain PCC 7120 hetY Gene Influences Heterocyst Development

2003 ◽  
Vol 185 (23) ◽  
pp. 6995-7000 ◽  
Author(s):  
Ho-Sung Yoon ◽  
Martin H. Lee ◽  
Jin Xiong ◽  
James W. Golden
Keyword(s):  
Atp Binding ◽  
Binding Motif ◽  
Filamentous Cyanobacterium ◽  
Hypothetical Proteins ◽  
Nitrogen Fixing ◽  
Fixed Nitrogen ◽  
Anabaena Sp ◽  
Time Required ◽  
Pcc 7120 ◽  
Heterocyst Development

ABSTRACT The filamentous cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120 responds to starvation for fixed nitrogen by producing a semiregular pattern of nitrogen-fixing cells called heterocysts. Overexpression of the hetY gene partially suppressed heterocyst formation, resulting in an abnormal heterocyst pattern. Inactivation of hetY increased the time required for heterocyst maturation and caused defects in heterocyst morphology. The 489-bp hetY gene (alr2300), which is adjacent to patS (asl2301), encodes a protein that belongs to a conserved family of bacterial hypothetical proteins that contain an ATP-binding motif.

alr0117, a two-component histidine kinase gene, is involved in heterocyst development in Anabaena sp. PCC 7120

Microbiology ◽  
2004 ◽  
Vol 150 (2) ◽  
pp. 447-453 ◽  
Author(s):  
Degang Ning ◽  
Xudong Xu
Keyword(s):  
Histidine Kinase ◽  
Regulatory System ◽  
Gene Encoding ◽  
Kinase Gene ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Polysaccharide Layer ◽  
Heterocyst Development

Anabaena sp. PCC 7120 was mutagenized by transposon Tn5-1087b, generating a mutant whose heterocysts lack the envelope polysaccharide layer. The transposon was located between nucleotides 342 and 343 of alr0117, a 918 bp gene encoding a histidine kinase for a two-component regulatory system. Complementation of the mutant with a DNA fragment containing alr0117 and targeted inactivation of the gene confirmed that alr0117 is involved in heterocyst development. RT-PCR showed that alr0117 was constitutively expressed in the presence or absence of a combined-nitrogen source. hepA and patB, the two genes turned on during wild-type heterocyst development, were no longer activated in an alr0117-null mutant. The two-component signal transduction system involving alr0117 may control the formation of the envelope polysaccharide layer and certain late events essential to the function of heterocysts.

Early candidacy for differentiation into heterocysts in the filamentous cyanobacterium Anabaena sp. PCC 7120

2009 ◽  
Vol 192 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Masakazu Toyoshima ◽  
Naobumi V. Sasaki ◽  
Makoto Fujiwara ◽  
Shigeki Ehira ◽  
Masayuki Ohmori ◽  
...  
Keyword(s):  
Filamentous Cyanobacterium ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

scholarly journals The amt Gene Cluster of the Heterocyst-Forming Cyanobacterium Anabaena sp. Strain PCC 7120

2008 ◽  
Vol 190 (19) ◽  
pp. 6534-6539 ◽  
Author(s):  
Javier Paz-Yepes ◽  
Victoria Merino-Puerto ◽  
Antonia Herrero ◽  
Enrique Flores
Keyword(s):  
Ammonium Nitrate ◽  
Nitrogen Source ◽  
Gene Cluster ◽  
Free Medium ◽  
Combined Nitrogen ◽  
Laboratory Conditions ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120

ABSTRACT The genome of the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 bears a gene cluster including three amt genes that, based on homology of their protein products, we designate amt4, amt1, and amtB. Expression of the three genes took place upon ammonium withdrawal in combined nitrogen-free medium and was NtcA dependent. The genes were transcribed independently, but an amt4-amt1 dicistronic transcript was also produced, and expression was highest for the amt1 gene. A mutant with the whole amt region removed could grow under laboratory conditions using ammonium, nitrate, or dinitrogen as the nitrogen source.

scholarly journals c-di-GMP Homeostasis Is Critical for Heterocyst Development in Anabaena sp. PCC 7120

2021 ◽  
Vol 12 ◽  
Author(s):  
Min Huang ◽  
Ju-Yuan Zhang ◽  
Xiaoli Zeng ◽  
Cheng-Cai Zhang
Keyword(s):  
Nitrogen Starvation ◽  
Filamentous Cyanobacterium ◽  
Nitrogen Deprivation ◽  
Heterocyst Differentiation ◽  
Combined Nitrogen ◽  
Heterocyst Frequency ◽  
Genes Encoding ◽  
Anabaena Sp ◽  
Opposing Effects ◽  
Pcc 7120

c-di-GMP is a ubiquitous bacterial signal regulating various physiological process. Anabaena PCC 7120 (Anabaena) is a filamentous cyanobacterium able to form regularly-spaced heterocysts for nitrogen fixation, in response to combined-nitrogen deprivation in 24h. Anabaena possesses 16 genes encoding proteins for c-di-GMP metabolism, and their functions are poorly characterized, except all2874 (cdgS) whose deletion causes a decrease in heterocyst frequency 48h after nitrogen starvation. We demonstrated here that c-di-GMP levels increased significantly in Anabaena after combined-nitrogen starvation. By inactivating each of the 16 genes, we found that the deletion of all1175 (cdgSH) led to an increase of heterocyst frequency 24h after nitrogen stepdown. A double mutant ΔcdgSHΔcdgS had an additive effect over the single mutants in regulating heterocyst frequency, indicating that the two genes acted at different time points for heterocyst spacing. Biochemical and genetic data further showed that the functions of CdgSH and CdgS in the setup or maintenance of heterocyst frequency depended on their opposing effects on the intracellular levels of c-di-GMP. Finally, we demonstrated that heterocyst differentiation was completely inhibited when c-di-GMP levels became too high or too low. Together, these results indicate that the homeostasis of c-di-GMP level is important for heterocyst differentiation in Anabaena.

scholarly journals Functions of the Essential Gene mraY in Cellular Morphogenesis and Development of the Filamentous Cyanobacterium Anabaena PCC 7120

2021 ◽  
Vol 12 ◽  
Author(s):  
Jing Liu ◽  
Wei-Yue Xing ◽  
Ju-Yuan Zhang ◽  
Xiaoli Zeng ◽  
Yiling Yang ◽  
...  
Keyword(s):  
Cell Division ◽  
Time Window ◽  
Essential Gene ◽  
Synthetic Activity ◽  
Filamentous Cyanobacterium ◽  
Cell Width ◽  
Cyanobacterium Anabaena ◽  
Bacterial Cell Shape ◽  
Pcc 7120 ◽  
Heterocyst Development

Bacterial cell shape is determined by the peptidoglycan (PG) layer. The cyanobacterium Anabaena sp. PCC 7120 (Anabaena) is a filamentous strain with ovoid-shaped cells connected together with incomplete cell constriction. When deprived of combined nitrogen in the growth medium, about 5–10% of the cells differentiate into heterocysts, cells devoted to nitrogen fixation. It has been shown that PG synthesis is modulated during heterocyst development and some penicillin-binding proteins (PBPs) participating in PG synthesis are required for heterocyst morphogenesis or functioning. Anabaena has multiple PBPs with functional redundancy. In this study, in order to examine the function of PG synthesis and its relationship with heterocyst development, we created a conditional mutant of mraY, a gene necessary for the synthesis of the PG precursor, lipid I. We show that mraY is required for cell and filament integrity. Furthermore, when mraY expression was being limited, persistent septal PG synthetic activity was observed, resulting in increase in cell width. Under non-permissive conditions, filaments and cells were rapidly lysed, and no sign of heterocyst development within the time window allowed was detected after nitrogen starvation. When mraY expression was being limited, a high percentage of heterocyst doublets were found. These doublets are formed likely as a consequence of delayed cell division and persistent septal PG synthesis. MraY interacts with components of both the elongasome and the divisome, in particular those directly involved in PG synthesis, including HetF, which is required for both cell division and heterocyst formation.

Function analysis of RNase E in the filamentous cyanobacterium Anabaena sp. PCC 7120

2020 ◽  
Vol 171 (5-6) ◽  
pp. 194-202
Author(s):  
Huaduo Yan ◽  
Yarui Cheng ◽  
Li Wang ◽  
Wenli Chen
Keyword(s):  
Function Analysis ◽  
Filamentous Cyanobacterium ◽  
Rnase E ◽  
Cyanobacterium Anabaena ◽  
Anabaena Sp ◽  
Pcc 7120
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